Grinding machine



g- 11, 1953 H. A. SILVEN 2,648,172

GRINDING MACHINE Filed April 11, 1952 3 'sheets sheet 1 ITH/GTITOI" HERBER T A. SILVEN By ATTorr/e Aug. 11, 1953 Filed April 11, 1952 H. A. SILVEN GRINDING MACHINE 3 Sheets-Sheet 2 IIIIIIIIII ||||||u mu -Ir'1venTor H RBERT A SILVEN B W-I- UD.EJ ATTorne Aug. 11, 1953 H. A. SILVEN 2,648,172

GRINDING MACHINE Filed April 11, 1952 s Sheejs-Sheet s Invenfor HERBERT A SILVEN Patented Aug. 11, 1953 GRINDING MACHINE Herbert A. Silven, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application April 11, 1952, Serial No. 281,731

2 Claims.

The invention relates to grinding machines, and more particularly to a speed control device automatically to maintain a uniform peripheral speed of the grinding wheel.

One object of the invention is to provide a simple and thoroughly practical speed control mechanism automatically to maintain a substantially uniform peripheral speed on the grinding wheel. Another object is to provide an automatically actuated rheostat control for varying the speed of the grinding wheel driving motor so as to maintain a substantially constant peripheral speed of the grinding wheel as it wears away. Another object is to provide an automatically actuated speed control mechanism which is actuated by and in timed relation with the truing tool feeding mechanism for increasing the rotative speed of the grinding wheel as it wears away so as to maintain a substantially constant peripheral speed thereof. Another object of the various possible embodiments of the mechanical features of the invention:

Figure 1 is a fragmentary front elevation, partly in section, of a wheel slide, Wheel truing apparatus and a grinding wheel speed control mechanism; and

Figure 2 is a fragmentary sectional view, on an enlarged scale, through the truing apparatus feed mechanism;

Figure 3 is a hydraulic piping diagram of the actuating mechanism;

Figure 4 is an electric diagram of the controls for the wheel driving motor; and

Figure 5 is a fragmentary View of a modified form of the driving connection between the truing tool feeding mechanism and the speed control mechanism.

A grinding machine has been illustrated in the drawings comprising a base II! which serves as a support for a rotatable work support (not shown) This work support may be identical with that shown in the prior U. S. Patent No. 2,522,485 to H. A. Silven and C. G. Flygare dated September 12, 1950, to which references may be had for details of disclosures not contained herein.

The base II! also serves as a support for a transversely movable wheel slide H which is arranged to slide transversely on a V-way l2 and a flat-way l3 formed on the upper surface of the base l0.

' A suitable feeding mechanism is provided for causing a transverse movement of the slide l l relative to the base In comprisin a half nut I 4 depending from the under side of the wheel slide II. The half nut l4 meshes with or engages a rotatable feed screw I5. The feed screw I5 may be actuated by any of the Well known conventional feeding mechanisms.

Wheel slide ll serves as a support for a rotatable Wheel spindle l6 which is journaled in spaced bearings (not shown). The wheel spindle l6 supports a grinding wheel I! on its left hand end (Fig. 1). The grinding wheel I! is partially surrounded by a wheel guard l3 which is fastened to the wheel slide l l.

A suitable driving mechanism is provided for the spindle I6 comprising a variable speed electric motor which is mounted on the upper surface of the wheel slide II. The motor 20 is provided with a motor shaft 2| having a multiple V-groove pulley 22 mounted thereon which is connected by multiple V-belts 23 with a multiple V-groove pulley 24 which is mounted on the right hand end of the wheel spindle IS. A rheostat 25 having an actuatin shaft 26 is provided for varying the speed of the motor 20.

The wheel guard I 8 supports a housing 30 having a plane upper surface which in turn supports bracket 3| for supporting a grinding wheel truin apparatus. A slide base 32 is fixedly supported on the bracket 3| by means of clamping screws 33 and 34. The slide base 32 serves as a support for alongitudinally movable slide 35 which is arranged to slide longitudinally on a dove-tailed slideway 36 formed on the slide base 32.

A hydraulically operated mechanism is provided for traversing the slide 35 longitudinally comprising a cylinder 31 which contains a slidably'mounted piston 38. The piston 38 is connected to the left hand end of a piston rod 39 (Fig. 3), the other end of which is fastened to an end cap 40 fixed on the end of a slide 35. A pair of nuts serve to lock the piston rod 39 to the end cap 40. Theend cap 40 carries a stop screw 42 which is arranged to engage the end of the cylinder 3-! to facilitate limiting the movement of the slide 35 toward the left. When fluid under pressure is passed through a pipe 45 into a cylinder chamber, the piston 38 together with the slide 35 will move toward theright (Fig.

3). During this movement of the piston 38, fluid within a cylinder chamber 48 may exhaust through a pipe 41.

A suitable control mechanism is provided fo the cylinder 31 comprising a rotary type reversing valve 58 having a valve rotor 5| which may be manually actuated by a control lever 52. When fluid under pressure is passed through a pipe 49 from a suitable source of supply, it p s into a valve chamber 53, through a traverse passage 54 formed in the valve rotor 5| into a valve chamber 55 and through the pipe 47;.into the cylinder chamber 48 to cause the piston 38 to move toward the left. This movement: of the piston 38 and the slide 35' toward the'left continues until the stop screw 42 engages the right hand end of the cylinder 31. 1 Duringmovement;

of the piston 38 toward the left, fluid within the cylinder chamber 46 may exhaust through "thepipe 45 into a valve chamber 56, through a traverse passage 5'I in the valve= rtor5 I into a valve chamber 58 and out through an exhaust pipe 59 and through athrottle valve-80- By manipulation of the throttle valve 68, the speed of movement of the piston 38, and the wheel slide 35 may be readily varied and controlled as desired.

When it is desired toreverse the direction of the movement of theslide 35, the control lever 52 will be moved in aclockwise direction into the broken line position 5211 (Fig. 3) which. move.- ment shifts the valve rotor I so'that fluid under pressure from the pipe 49 passes into the valvechamber 56-, through the pipe 45 into the cylinder chamber 46 to' cause the piston 33 and the slide 35 to move longitudinally toward the right. During this movement fluid within the cylinder chamber 48' may exhaust through the pipe 41, into the valve-chamber 55, through the transverse passage 54 and out through the pipe 58 and the-throttle valve 60-.

The longitudinally movable slide 35serves as a support for a vertically arrangedhousing 64. The housing 64 is provided with apair of spaced bearings 65- and 68 which support a vertically arranged-truing tool carrier 61' having a truing tool mounted at its lower end.

A suitable feeding mechanism is provided for feeding the carrier 61' vertically in either direction relative to the slide 35-. This mechanism preferably comprises a nut and screw' feeding mechanism in which a screw threaded portion 69 is provided on the upper end of the. carrier 61. A rotatable nut meshing with r engaging the threaded portion 68: is providedwith an integral flange II which is rotatably supported on the carrier 64 bya. pair. of plates I2 and 1-3.

A manually operable-feed wheel is mounted on the lower end of a vertically'arranged rotatable shaft 16 which is rotatably supported a housing 11. The housing" is fixedl mounted relative to the housing 64., The upper end o the shaftv I6 is, provided-with. a'pinion 18 which meshes with a gear I8 keyed on the. periphery of the nut 10.. It, will be readily apparentfrom the foregoing disclosure that arotary motion of the hand wheel 15 will" be imparted through the mechanismv above described to rotate the nut 10 and thereby impart a-vertical movement to the truing tool carrier 61. The direction of rotation of the hand wheel I5 serves to determine the direction of movement of the carrier 61. In order to facilitate locking thecarrier 6-! in an adjusted position, a. spring pressed detent 80 is arranged to engage-the teeth of1a gear 8 I; which is keyed on the upper end of the shaft I6. When it is desired to adjust the position of the truing tool 68, the detent is moved in a direction toward the left (Fig. 2) to disengage the detent from the gear 8| after which the feed wheel 75 may be rotated to cause the desired vertical movement of the truing tool carrier 61 and the truing tool 68.

As shown in Figure 4, power lines 84 and 85 are provided for supplying electric power to th motor 20. A start switch 86 is provided which .when. closed serves to energize a relay switch 81 which when energized serves to pass current through the rheostat 25 to rotate the motor 20. A stop switch 88 is provided whereby the motor 28 may be stopped at any time during the grinding operationas desired.

A suitable connection is provided between th feeding mechanism above described and the rheostat so that when the truing tool is fed toward the periphery of..the grinding wheel IT for a truing operation, also a corresponding motion is imparted to the rheostat control shaft 26 so as to adjust the rheostat as the grinding wheel wears away due, to normal wheel Wear and also to the truing feed so as to maintain a substantiall constant peripheral. speed on the periphery of the grinding wheel at all times. As the wheel reduces in size, the motors-peed is increased by means Of the rheostat to increase the rotative speed of the wheel I I so that the surface speed thereof remains substantially constant. As illustrated in Figure l, a flexible shaft 90 is provided for connecting the wheel feeding mechanism of the truing apparatus with the shaft'ZB of the rheostat 25. The upper end of the flexible shaft 90 is provided with a pinion 9| which meshes with the gear 18 on th truing tool feeding mechanism. The lower end of the flexible shaft 98 is connected to a drive shaft 92 on a conventional gear reduction unit 83. The drive'shaft 94 of the unit 83 is connected by a coupling 85. with the rheostat control shaft 26. It will be readily apparent from the foregoing disclosure. that actuation of the feed wheel 15 will be imparted through the gear I9 and the gear 8| to impart a rotary motion to the rheostat control shaft 26 so as automatically to adjust the speed of the motor 20.

A modification has been illustrated in Figure 5 in which the vertical movement of the truing tool carrier 61 is utilized to impart a compensating adjustment to the rheostat 25. As illustrated in Figure 5, the upper end of the carrier screw 59 is provided with an outwardly extending arm I08, the outer end of which rides in a vertical groove IDI formed in a bracket I82. The arm I65! serves to hold the screw 69 and the carrier 61 against rotary motion. A rack bar IE3 is fastened at its upper end to the arm I80. The rack bar I53 meshes with a gear I84 mounted on the upper end of a flexible drive shaft I05, the lower end of the flexible shaft I05 is connected with the control shaft 26 of the rheostat 25. It will be readil apparent from the foregoing disclosure that when the carrier 61 and the screw 68 are moved vertically, a corresponding movement will be imparted to the rack bar I03 which in turn imparts a 1'0- tary motion through the gear I04, the flexible shaft I05 to the control shaft 26 of the rheostat 25.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successively achieved. As many possible embodiments-may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth, or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a grinding machine having a transversely movable wheel slide, a rotatable wheel spindle thereon, a grinding wheel on said spindle, means including an electric motor on said slide to rotate said spindle, a rheostat on said slide operatively connected to control the speed of said motor, a gear reducer unit on said slide operatively connected to actuate said rheostat, a truing apparatus on said slide including a longitudinally movable slide movable parallel with the axis of said wheel spindle, a transversely movable carrier on said latter slide, a truing tool carrier thereon, a manually operable nut and screw feed mechanism interposed between the truing apparatus slide and the carrier for feeding the truing tool toward and from the grinding wheel, and operative connections including flexible shaft, one end of which is operatively connected to said feeding mechanism and the other end of which is operatively connected to said gear reducer unit whereby actuation of the feeding mechanism automatically actuates said rheostat to adjust the speed of said motor so as to maintain a constant peripheral speed of the grinding wheel as it wears away.

2. In a grinding machine having a transversely movable wheel slide, a rotatable wheel spindle thereon, a grinding wheel on said spindle, means including an electric motor on said slide operatively connected to rotate said spindle, a rheostat on said slide to control the speed of the said motor, a gear reducer unit on said slide operatively connected to actuate said rheostat, a truing apparatus on said slide supporting a longitudinally movable slide movable parallel with the axis of said wheel spindle, a transversely movable carrier on said truing apparatus slide, a truing tool on said carrier, a manually operable feed mechanism interposed between the truing apparatus slide and the carrier for feeding the truing tool toward and from the grinding wheel, a flexible shaft, a gear connecting one end of said shaft to said feeding mechanism, and a coupling connected to the other end of said shaft to said gear reducer unit whereby actuation of the feeding mechanism automatically actuates said rheostat to vary the speed of said motor so as to maintain a uniform peripheral speed of the grinding wheel as it wears away.

HERBERT A. SILVEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,162,038 Tribble June 13, 1939 2,190,132 Alvord Feb. 13, 1940 2,302,304 Ehberty Nov. 17, 1942 2,454,988 Bunker Nov. 30. 1948 

